This invention is generally concerned with a method of monitoring a tire-condition value in a pneumatic tire and more particularly with a method of automatically monitoring a tire-condition value in a pneumatic tire of a moving vehicle.
This application is related to concurrently filed application entitled A SYSTEM OF APPARATUS FOR MONITORING A TIRE CONDITION VALUE IN A PNEUMATIC TIRE Ser. No. 09/820,440.
It is known in the art to combine a passive radio frequency (RF) transponder, having a RF antenna, with a tire-condition sensor and to incorporate the resulting electronic tag with a pneumatic tire. The transponder typically includes an integrated circuit that is preferably a suitable complimentary, metal-oxide, semiconductor (CMOS). The integrated circuit generally includes a logic circuit and a read only memory (ROM) circuit connected thereto. The ROM circuit preferably has stored therein a unique serial number (SN) for identifying the electronic tire tag and thus the tire with which it is incorporated. In addition, the integrated circuit typically includes an analog to digital (A/D) converter circuit that is connected between the logic circuit and the sensor, for receiving and converting respective analog sample signals received from the sensor to respective related digital signals for processing by the logic circuit. Moreover, the integrated circuit typically includes an RF rectifier circuit that is connected between the RF antenna and the logic circuit, for receiving therefrom and rectifying an RF signal, transmitted from an external transceiver, for providing a direct current (D.C.) power input signal to the logic circuit. Still further, the integrated circuit includes a clock signal generating circuit that is also connected between the RF antenna and the logic circuit for receiving the RF signal and generating therefrom a suitable timing signal for use by the logic circuit. Moreover, the logic circuit includes a transmitter circuit. And, the logic circuit is constructed and arranged to respond to receiving the D.C power input signal for energizing the ROM circuit, the A/D converter circuit and the sensor, and for causing the transmitter circuit to transmit to of the external transceiver, data corresponding to the SN and to the then current sample signal received from the sensor.
The above-described electronic tire tag is typically incorporated with a pneumatic tire by initially encapsulating the tag in a rigid or semi-rigid material, such as a urethane, epoxy or polystyrene resin, hard rubber compound or the like. Thereafter, the encapsulated tag is normally wrapped with a green rubber material to form a patch that is fixedly secured to a previously cured pneumatic tire. Alternatively, the encapsulated tag may be included between respective layers of green-rubber material forming an uncured tire and vulcanized therewith, to form a cured pneumatic tire having the encapsulated electronic tire tag embedded therein.
As shown in U.S. Pat. No. 5,712,609, issued Jan. 27, 1998 to Mehregany et al., it is also known in the art to provide a micro-mechanical temperature condition sensor, fabricated on a silicon or bimetallic substrate, that is constructed and arranged for sensing a threshold temperature value. As discussed in the ""609 Patent, when an extreme temperature condition eventuates and is sensed by a micro-mechanical temperature sensor, the sensor latches and remains latched to provide a memory of the event available for detection purposes. Due to such characteristics, the micro-mechanical temperature sensor has come to be known in the art as a maximum temperature memory switch (MTMS). Assuming the provision of an MTMS as the sensor in the electronic tire tag discussed above, the A/D converter may be eliminated since the MTMS is a digital device. Moreover, the logic circuit would then be constructed an arranged to respond to energization thereof for performing a continuity detection test of the MTMS to determine the latched or unlatched state of the MTMS and to cause the transmitter circuit to transmit, to the external transceiver, data corresponding to the SN, followed by data corresponding the latched or unlatched state of the MTMS.
As shown in U.S. Pat. No. 4,067,235, issued Jan. 10, 1978 to Markland et al., it is also known in the art to provide a system for remotely measuring the air pressure in a pneumatic tire. The system calls for the provision of an electronic tire tag that includes a passive transponder and a pressure sensor in a pneumatic tire. In addition, externally of the tire the system includes a stationary power transmitter that generates an electromagnetic field in the roadway with a flat coil antenna for empowering the transponder and pressure sensor. Moreover, the system includes a signal processor. When the pressure sensor is empowered, the sensor transmits a low frequency FM signal representative of the tire pressure to the signal processor. Whereupon the signal processor generates quantitative signals representing the pressure in the tire, and visually displays and passes such signals to a computer. By means of various flat coil antenna configurations, the system can distinguish between tires mounted in various relationships. Moreover, by coding the FM signal the system can uniquely identify the vehicle as well as each tire thereof. In an additional embodiment, a current induced therein by an external magnetic field powers the pressure sensor. This embodiment calls for the pressure sensor in the tire to be rotated through a stationary magnetic field generated by permanent magnets attached to the vehicle.
Moreover, as shown in International Patent Application Publication Number WO90/12474, published Oct. 18, 1990, it is known in the art to provide system for electronically identifying a vehicle tire having a coil and signal generator internally secured to the tire. As the vehicle and thus the tire moves in a predetermined path of travel, the signal generator in the tire responds to the presence of predetermined signals at the coil, that are received from an interrogator antenna oriented at an angle of substantially 45 degrees relative to the path of travel of the vehicle, by transmitting a unique signal identifying the signal generator.
Other publications of interest found in the course of a prior art search, concerning the subject matter of the present invention, are U.S. Pat. Nos. 3,752,960 and 4,630,044 and 5,070,334.
According to the invention there is provided a method of monitoring at least one tire condition value of each of a plurality of tires of a moving vehicle, in a system of apparatus for monitoring the at least one tire condition value of each of the tires. Each of the tires has associated therewith an electronic tire tag for sensing the at least one tire condition value of the associated tire, and the monitoring system has portable vehicle sensing apparatus and portable ramp apparatus, tire sensing apparatus, portable transceiver apparatus and has portable computer apparatus removably electrically connected thereto and to the vehicle sensing apparatus and tire sensing apparatus. The method comprises the steps of the computer apparatus determining whether the vehicle sensing apparatus has sensed the moving vehicle and the ramp apparatus supporting the moving vehicle. In addition the method includes the steps of the computer apparatus determining whether respective tires of the moving vehicle have been sensed by the tire sensing apparatus, and causing the transceiver apparatus to transmit an interrogation signal when the tire sensing apparatus senses at least one tire. Further, the method includes the step of the transceiver apparatus receiving and demodulating modulated tire tag signals independently of one another from different tire tags for providing different demodulated tire tag signals. Moreover, the method includes the step of the transceiver apparatus digitizing the different demodulated tire tag signals and providing corresponding different digital tire tag signals to the computer apparatus. And, the method includes the step of the computer apparatus processing the different digital tire tag signals.
The method may also include the step of the vehicle sensing apparatus providing a vehicle sensing signal to the computer apparatus when the moving vehicle is sensed, and the computer apparatus providing an enabling signal to the transceiver apparatus upon receiving the vehicle sensing signal. In addition, the method may include the step of the tire sensing apparatus providing a tire sensing signal to the computer apparatus upon sensing the at least one tire, and the computer apparatus providing a start interrogation signal to the transceiver apparatus upon receiving the tire sensing signal. further the processing step of method may include the step of obtaining from each of the digital tire tag signals data corresponding to at least one tire condition value selected from a group consisting of a tire air pressure value, a tire air temperature value, an internal tire temperature value and an MTMS status value. And the processing step of the method may include the steps of sorting and formatting the at least one tire condition value obtained from each of the digital tire tag signals. Moreover, the processing step may include the steps of sorting and displaying the at least one tire condition value obtained from each of the digital tire tag signals.
Further, assuming the computer apparatus has ambient pressure and temperature value measuring apparatus for obtaining therefrom current ambient temperature and pressure values, the method may include the step of the computer apparatus adjusting at least one of the values obtained from the digital tire tag signal in consideration of at least one of the current ambient temperature and pressure values. Furthermore, assuming each of the tire tags has a different serial number, and the processing step of the method may include the step of obtaining from the digital tire tag signals data corresponding to the different serial numbers. In addition the processing step of the method may include the step of processing data obtained from the respective digital data signals in accordance with customer requirements. Still further, the processing step may include the step of accounting for a total number and deployment of the vehicle tires. In addition, the method may include the step of the computer apparatus determining whether the moving vehicle is no longer sensed by the vehicle sensing apparatus, and the computer apparatus permitting the transceiver apparatus to continue transmitting the interrogation signal until the moving vehicle is no longer sensed. Further the processing step may include the step of generating a date and time of receiving each of the digital tire tag signals. Still further, the method may include the step of the computer apparatus determining whether a previous count of a predetermined time period has been commenced, commencing the count upon determining that the count has not been commenced, and providing a stop interrogation signal to the transceiver apparatus for causing discontinuance thereby of the interrogation signal when the count ends.
In addition, the method may include the step of the computer apparatus determining whether respective tires of the moving vehicle have been sensed by the tire sensing apparatus until the vehicle is no longer sensed. Moreover the method may include the step of the computer apparatus commencing a count of a predetermined time interval when the computer apparatus stops receiving the tire sensing signals, and causing the transceiver apparatus to continue transmission of the interrogation signal until the count ends. The method may also include the step of the computer apparatus providing a stop interrogation signal to the transceiver apparatus for causing discontinuance thereby of the interrogation signal when the count ends. Further, the method may also include the step of the computer apparatus providing a shutdown signal to the transceiver apparatus when the vehicle is no longer sensed and the transceiver apparatus executing a shutdown routine upon receiving the shutdown signal. In addition, the method may include the step of the computer apparatus determining whether another vehicle has been sensed after the computer apparatus provides the shutdown signal to the transceiver apparatus. And, the method may include the step of the computer apparatus storing data corresponding to the respective digital data signals for historical reference purposes.